DESCRIPTION: This proposal seeks to develop a commercially-available and completely internal intramedullary (IM) nail which, when fixed to a broken for osteotomized bone, can promote distraction osteogenesis in humans. The device will be non-invasively powered by an external power system and will be precisely controlled by a computer. This new type of implantable nail for leg lengthening does not rely upon external fixation, transcutaneous cables or wires. It will provide a more comfortable and potentially safer method of limb lengthening over current technology. A prototype device has been tested and built. The protocol of Phase II animal trails will be based upon the results of bench testing of an existing prototype which will be further developed and designed to fit canine femorae in Phase I. PROPOSED COMMERCIAL APPLICATION: Phase I of this proposal is the first step toward a commercially- available, completely internal, intramedullary device for distraction osteogenesis. This implant will replace contemporary external fixators for limb lengthening procedures. This implant possesses the unique potential to sense bone stiffness and provide the clinician with a way to monitor the progress of bone regeneration. Using a feed-back control system, implant actuation (lengthening and oscillation) could be regulated by the bone stiffness desired.